1. Field of the Invention
The present invention relates, in general, to a chemical mechanical polishing (CMP) apparatus and, more particularly, to a CMP apparatus that measures the vibration acceleration of a CMP pad conditioner for conditioning a CMP pad, thereby making it possible to predict the wear rate of the CMP pad conditioner, to check a state of the CMP pad conditioner, and to maintain the CMP pad conditioner in a steady state.
2. Description of the Related Art
In semiconductor apparatuses, CMP technology is used to flatten thin layers such as insulating layers or metal layers formed on semiconductor wafers.
The main expendable supplies used in a CMP process may include a CMP pad, slurry, and a CMP pad conditioner. Above all, the CMP pad conditioner is equipped with a grinder such as a diamond grinder that makes contact with the CMP pad to scrape or rub a surface of the CMP pad, thereby serving to perform a conditioning function in order to optimize a surface state of a new CMP pad to the initial state in which the ability of the CMP pad to hold the slurry is good or to restore the ability of the CMP pad to hold slurry so as to maintain the polishing capability of the CMP pad in a steady state, and to improve fluidity of the slurry fed to the CMP pad.
In the CMP process, the removal rate of a wafer can be measured, whereas the wear rate of the CMP pad cannot.
A constant wear rate of the CMP pad means that the surface state of the CMP pad is constant. The meaning of “the surface state of the CMP pad is constant” implies the capability of maintaining the removal rate of the wafer constant. Further, when the wear rate of the CMP pad is significantly decreased or increased, this exerts an influence on the removal rate of the wafer as well as defects of the wafer. Thus, it is very important to that the wear rate of the CMP pad be constant in the CMP process.
However, although the wear rate of the CMP pad can be predicted based on the removal rate of the wafer, no apparatus and method capable of predicting the wear rate of the CMP pad have been proposed that exclude a method of measuring the removal rate of the wafer. Further, conventional CMP apparatuses cannot check the state in which the CMP pad conditioner is being used or installed.
Thus, there is a need for a CMP apparatus capable of predicting the wear rate of the CMP pad without measuring the removal rate of the wafer or the state in which the CMP pad conditioner is being used or installed.